Multilayer Dental Appliances And Related Methods And Systems
Patent No. US11154384 (titled "Multilayer Dental Appliances And Related Methods And Systems") was filed by Align Technology Inc on Mar 26, 2021.
What is this patent about?
’384 is related to the field of orthodontics, specifically to dental appliances used for repositioning teeth. Traditional methods involve braces, while newer systems use a series of preformed aligners to gradually move teeth. There's a need for improved aligner materials that provide continuous force and better occlusion, reducing the need for mid-course corrections and fewer aligners overall.
The underlying idea behind ’384 is to create a multilayer aligner with improved mechanical properties. This is achieved by sandwiching a hard polymer layer between two soft polymer layers. The combination aims to provide both the rigidity needed for force application and the flexibility for patient comfort and appliance durability.
The claims of ’384 focus on a dental appliance comprising tooth-receiving cavities and three or more polymer layers. Specifically, the independent claims require a hard polymer layer made of co-polyester with a flexural modulus greater than 150,000 psi, and a soft polymer layer made of thermoplastic polyurethane elastomer with an elongation at break greater than 200% and a hardness between 60 A and 85 D. Some claims extend to a plurality of such appliances for sequential tooth movement.
In practice, the multilayer sheet is thermoformed over a model of the patient's teeth in the desired position. The hard layer provides the necessary stiffness to apply force to the teeth, while the soft layers enhance comfort and prevent cracking or deformation of the aligner during use. The specific material choices, co-polyester for the hard layer and thermoplastic polyurethane elastomer for the soft layers, are crucial for achieving the desired balance of properties.
This design differentiates itself from prior aligners by using a specific combination of materials and a multilayer structure. Tests show that aligners made with this multilayer sheet exhibit improved stress relaxation properties, better long-term unloading characteristics, and enhanced long-term movement compared to existing aligner materials. This translates to more consistent force application over time, potentially leading to more predictable and efficient tooth movement.
How does this patent fit in bigger picture?
Technical landscape at the time
In the early 2010s when ’384 was filed, aligner-based orthodontic treatments were gaining traction at a time when computer-aided design and manufacturing (CAD/CAM) was typically used to create customized aligners based on a series of incremental tooth arrangements. At that time, the mechanical properties of aligner materials, such as durability and elasticity, were important considerations when systems commonly relied on single-layer polymer sheets to apply force to teeth.
Novelty and Inventive Step
The examiner approved the patent because the prior art, specifically DeSimone et al., teaches methods of making dental appliances with a sheet comprising a hard polymer layer and a soft polymer layer. However, DeSimone does not teach or suggest a sheet comprising three or more polymer layers, where the three or more polymer layers include a hard polymer layer with a flexural modulus greater than about 150,000 psi and a soft polymer layer comprising a thermoplastic polyurethane elastomer with specific elongation and hardness properties. The examiner determined that one of ordinary skill in the art would not have been reasonably motivated to modify DeSimone to achieve the claimed invention, which provides appliances with teeth-receiving cavities that apply a resilient positioning force.
Claims
This patent contains 30 claims, with independent claims 1, 11, and 21 directed to dental appliances comprising multiple polymer layers for teeth positioning. The dependent claims generally specify characteristics, materials, and dimensions of the polymer layers and dental appliances described in the independent claims.
Key Claim Terms New
Definitions of key terms used in the patent claims.
Patent Family
File Wrapper
The dossier documents provide a comprehensive record of the patent's prosecution history - including filings, correspondence, and decisions made by patent offices - and are crucial for understanding the patent's legal journey and any challenges it may have faced during examination.
Date
Description
Get instant alerts for new documents
US11154384
- Application Number
- US17214487
- Filing Date
- Mar 26, 2021
- Status
- Granted
- Expiry Date
- May 14, 2032
- External Links
- Slate, USPTO, Google Patents